OK, it won’t actually fly, it will float in a pool of gravity. More on that later.
Hubble has needed a sibling, a bigger, badder, swashbuckling, and more sensitive sibling. The James Webb Space Telescope (Webb) has been designed to supplement, not replace Hubble. Webb is bigger, way bigger than Hubble. Webb is 6.5 meters and Hubble is 2.4 meters. Webb will be badder due to its much higher sensitivity in the infrared end of the electromagnetic spectrum. Webb will be a swashbuckling sort of space telescope because, like Hubble currently, Webb will not have a repair or upgrade team available. When the Space Shuttle program existed, there was at least a chance to fix and/or upgrade Hubble. Not so now and not so for Webb. Even if Shuttles were still operating, Webb will be way beyond a Space Shuttle’s reach.
Webb will be on its own! If something critical breaks, an identical backup will take over. Redundancy will keep Webb going for decades…that’s the plan.
The riskiest events will be getting Webb into its gravity pool, setting up communications with its command center in Baltimore, unfolding its protective shade, and mirror. Webb’s mirror is made of 18 individual hexagonal mirrors (elements) that work together when in place. The mirror elements are arranged in three sections, a center section with 12 elements and two “wings” of 3 elements each, that are folded behind the center during launch. The wings will unfold and join with the center during its trip to final orbit. They must be positioned as designed for Webb to function as designed. The sunshade must be unfurled and positioned as designed to protect Webb from interfering infrared radiation. It must go as designed or be correctable from Baltimore, just under a million miles away!
Webb’s orbital destination is called L2, or Lagrange 2. It is one of five places in space where the Earth’s and Sun’s gravity cancel each other. I call it a gravity pool. A spacecraft in these places can pretty much just float there while orbiting the Sun.
Webb is different than Hubble. While Hubble is primarily an optical instrument with some infrared capability, Webb is primarily an infrared instrument, and that is why it needs to be so far from Earth. Our planet and the Moon both radiate a lot of infrared (heat). At its L2 position and with the sunshade in place, there is little infrared interference.
With its large size and deep infrared sensitivity, Webb will see through interstellar and intergalactic dust, significantly beyond what Hubble can see. That gets us farther back in time, to even earlier in our universe’s history.
Webb’s infrared eyes will also be able to detect planets out there, maybe even signs of life.
There will be amazing discoveries, all helping us better understand how it all happened.
When is launch? Latest schedule is December 18, 2021. Fingers crossed.
What’s in the Sky?
October 9; after sunset; southwest: A waxing crescent Moon is just above brilliant Venus
October 14; after sunset; south-southeast: A waxing gibbous Moon is between and below Jupiter and Saturn